Electric heating assemblies are known in the art. An assembly comprising a resistive heating element, which is usually coiled, and provides insulating supports for engaging the heating element. In a typical construction, a coiled resistive element is engaged by a plurality of insulators, and the insulators are in turn secured to a frame. The frame is made of wire and provides a rigid structure for supporting the resistive element. The frame is then inserted into a duct for contact with a stream of air flowing within the duct.
U.S. Pat. No. 3,486,003 (Cox) shows a heater assembly having upper and lower housing portions. Ceramic support elements extend across an open channel formed by the two housing portions. A resistive heater wire is wound around each of the ceramic support elements to heat air flowing through the channel. The heater wire has no span where it supports itself and is entirely coiled around a ceramic support element.
U.S. Pat. Nos. 1,679,841 (Shaw), 1,636,369 (Johnson), and 3,860,788 (Staples) are representative of heater assemblies wherein a rigid frame supports portions of a coiled electric resistance wire. The frame is placed in a duct which directs air past the heater element.
Other heater elements using a frame are shown in U.S. Pat. Nos. 4,337,390 (Best), 3,697,727 (Neuman, et al.) and 2,235,764 (Hynes).
U.S. Pat. No. 4,330,933 (Glucksman, et al.) shows a resistive heater element wound around a star-shaped carrier. The carrier is in turn supported within a duct.
U.S. Pat. No. 3,668,303 (Alexander) shows an electric heater assembly having triangular insulating elements which engage helically coiled resistive heating wire. The insulating supports are engaged by a wire frame to provide rigidity.
U.S. Pat. No. 737,689 (Wirt) shows a plurality of cylindrical support tubes having heater coil wire wound around their exteriors. A frame supports a plurality of these tubes to provide a heater assembly.